23 April 2024

Melody in valves: the “potato potato” of Harleys

Ah, the sound of Harley-Davidson, unique, right? The melody that their engines give off is so characteristic that it is impossible not to recognize it when a Harley passes nearby! This melody is special because of the also special design of the engine. If you have read our blog article “The engine of a motorcycle - How does it work? », you know how a gasoline engine works. A piston performs the intake, compression, combustion and exhaust strokes every two revolutions of the crankshaft. What you hear is the sound of compressed gases in the cylinder escaping when the exhaust valve opens. The melody produced – the famous “potato potato” – is due to the noise made by the opening of the exhaust valve when the crankshaft completes two revolutions. For what ? Because the crankshafts of Harley engines have only one axis and two pistons connected to it which move up and down in two cylinders positioned in a V shape. The consequence is that each spark produces combustion at unequal intervals. . . and therefore this fabulous noise. This melody of happiness is such that Harley Davidson went to court to prohibit Honda from copying it. In the 1990s, Honda attempted to challenge Harley Davidson's supremacy in the cruiser market in the United States. Harley Davidson did not accept that Honda not only attacked its flagship market, but also that Honda changed the configuration of its engine (from a double crankshaft to a single crankshaft) to imitate the Harley Davidson sound. . In 1994, Harley Davidson took Honda to court. Ultimately, Honda abandoned its strategy of conquering the cruiser market in the United States and the dispute did not find a legal outcome. The melody over the years is here.